Re: Temporal database - no end date

"DBMS_Plumber" <paul_geoffrey_brown_at_yahoo.com> wrote in news:1169403773.386629.255370_at_11g2000cwr.googlegroups.com:

>
> Yeah Frank. You see the standards to which we have so easily become
> acustomed.
>
> Let me explain it to Marshall, again.
>
> The answer "0.8 quanta" is not possible in the Date / Darwen /
> Lorentzos system, because (quoting them here - I'm the only one who's
> read the damn book, apparently) "Formally, however, time points are
> indeed points - they are indivisble, and the concept of duration
> strictly does not apply." You can't have "0.8" of a time quantum,
> because as DDL explicitly state, quantum are "indivisible".

I only started to read about the chronon. The articles that I read say that the application defines the granularity of chronon. Some one asked why is it that you cannot utilize the granularity of smaller value, one minute but not one day ? I am interested to know your opinion.

I work on Oracle and I can affirm that the DATE in Oracle is one second of granularity. You say that 0.8 of the quantum is impossible, 0.8 of the day is impossible but 0.8 of 24*3600 is possible. 1/7 of 1000 is not exact (142) but the error is < 0.1 per cent. Why one can not select the granularity of chronon to achieve the exactness ? You can say, go and use floating point, but floating point is not exact too.

>
> Because you can't use the DDL model to solve a wide variety of
> problems I, Joe, most folk who uses math to analyse time, and
> consequently most of the temporal DBMS research community, are obliged
> to reject the DDL model of time because it isn't a practical framework
> to model temporal operations.

I read about Snodgrass, and Snodgrass, he uses the name of chronon too. I want to know why you think that the chronon is bad in mathematic sense.

--
Tegi